Nano-structured dielectric composite

Abstract

A multilayer dielectric structure is formed by vacuum depositing two-dimensional matrices of nanoparticles embedded in polymer dielectric layers that are thicker than the effective diameter of the nanoparticles, so as to produce a void-free, structured, three-dimensional lattice of nanoparticles in a polymeric dielectric material. As a result of the continuous, repeated, and controlled deposition process, each two-dimensional matrix of nanoparticles consists of a layer of uniformly distributed particles embedded in polymer and separated from adjacent matrix layers by continuous polymer dielectric layers, thus forming a precise three-dimensional nanoparticle matrix defined by the size and density of the nanoparticles in each matrix layer and by the thickness of the polymer layers between them. The resulting structured nanodielectric exhibits very high values of dielectric constant as well as high dielectric strength.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention is related in general to nano-dielectric materials with plasmon-resonance electric-field effects tailored to enhance optical and dielectric properties. In particular, the invention pertains to a multilayer composite wherein three dimensional matrices of uniformly distributed nanoparticles are embedded between alternating continuous polymeric dielectric films.[0003]2. Description of the Related Art[0004]Electric energy storage devices, photovoltaics, displays, biosensors and a multitude of photonic devices could benefit greatly from advanced nano-dielectric materials that are tunable for particular electronic and optical applications. In general, nano-dielectric materials are evaluated for different performance characteristics of interest in various segments of the electromagnetic spectrum. For example, at low frequencies (1 Hz-1 MHz), the insulation properties of the material are important as they relate ...

AI Technical Summary

Benefits of technology

[0009]The invention is based on the concept of producing a nanocomposite dielectric material by alternating vacuum-deposited layers of nanoparticles and polymer dielectric layers of a specific thickness, so as to produce a structured, three-dimensional lattice of nanoparticles in a void-free polymeric dielectric material. As a result of the continuous and repeated deposition process used to produce this structure, each layer of nanoparticles consists of a layer of uniformly distributed particles embedded in polymer and separated from adjacent nanoparticle layers by continuous polymeric dielectric films that act as spacer layers, thus forming a precise three-dimensional nanoparticle matrix defined by the nanoparticle size and density and by the thickness of the polymer film that separates the nanoparticle layers. Crucial to the invention is the fact that the dielectric material is deposited as a liquid monomer that first engulfs the nanoparticles to form a void-free nanoparticle layer and then forms the spacer film in liquid form, thereby providing a leveling effect on the surface receiving the subsequent deposition of nanoparticles.

[0011]Each layer of nanoparticles is completely encapsulated by the monomeric dielectric layer deposited over it and is separated from the underlying nanoparticle layer by the previously deposited liquid monomer film which, upon curing, produces a level polymeric dielectric film upon which the nanoparticle layer is deposited. The leveling effect of the dielectric layer ensures that each nanoparticle layer is formed over a level surface so that each layer encompassing nanoparticles has a thickness essentially equal to the effective diameter of the particles. Inasmuch as the dielectric strength of a material is known to increase in thinner films, according to another aspect of the invention, the multilayer structure is formed with many nanoparticle layers separated by very thin dielectric spacer films, with at least ten, but preferably one hundred or more nanoparticle-layer / polymer-film pairs per micron thickness of the multilayer composite. Uniformity of nanoparticle size and density and precise thickness control of the polymer layer are critical aspects of the invention. These parameters can be controlled only by depositing the nanoparticles and the dielectric monomer in vacuum using a high speed continuous process where the layers are deposited sequentially on a moving substrate, such as a rotating drum or a flat substrate moving in reciprocating or rotating motion in a single plane

Problems solved by technology

At this stage of particle concentration, the dielectric constant of the composite becomes very high; however, the dissipation factor, the leakage current and the breakdown strength are compromised by the large clusters of agglomerated particles that short out segments of the dielectric.

This renders the high k material virtually unusable for high voltage dielectric applications.

However, higher voltage applications (e.g., 100V-1000V or higher) require that a large number of capacitors be connected in a series configuration, which is not practical because the cumulative series resistance and losses become prohibitively high.

Such structure, where particles are stacked to form a nanocomposite, can take advantage of the plasmon resonance effects in the optical part of the electromagnetic spectrum, but it is not applicable to lower frequency dielectric applications because materials that have gas inclusions in them are not appropriate for high strength dielectrics for capacitor, cables and transformer applications.

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